Estimation of parameters characterizing a steady-state synthesis process with nonlinear microorganism growth kinetics

The paper describes a theoretical basis developed for estimating the parameters of a steady-state biotechnological process characterized by nonlinear microorganism growth kinetics. This study aimed to obtain a common methodological basis for estimating input parameters that determine actual technology implementation, taking into account all possible restrictions on the concentration of incoming substrate Sf (g/l) and dilution rate D (h-1 ). The theory development was based on a mathematical model describing one of the most common processes of lactic acid production. This mathematical model includes three mass balance equations (for biomass, substrate, and product), as well as an equation of microorganism growth kinetics. The study established relations for calculating the ultimate value of the dilution rate D ult at a given Sf , relations for the maximum and minimum values of Sf , as well as Sf and D providing the maximum productivity value QP, g/(l·h), where QP = PD (P – product concentration, g/l). These relations were designed to calculate the parameters of possible process implementation for two options at the same value of QP: two values of D calculated for a given Sf and two values of Sf calculated for a given D. A numerical experiment is described using the constants of the mathematical model confirmed by foreign studies. This numerical experiment is illustrated using an Sf-D dependence pattern determining an acceptable value range for Sf and D, with the separate calculation of parameters according to Sf sections. For each of these sections, calculation formulas are provided. It is concluded that the developed theoretical basis is sufficiently general in nature to be applied to biotechnological processes that involve other kinetic relations, as well as microorganism strains creating by-products and using raw materials that are employed to reproduce the substrate in the process of synthesis.

Plant substrate as a vehicle for trituration: a pilot study

Motivation: Lactose and hydroalcoholic solutions are not the proper substances to study the High Dilution (HD) effects using plant models. Plant substrate can not be considered an inert vehicle, but it is not harmful to plants. Aim: In this pilot study we verify the possibility to use plant substrate as a trituration vehicle to prepare substances to be used in plants. Methods: We used a partially dried commercial plant substrate (12% humidity) as the vehicle to prepare a set of trituration, having NaCl as the initial active substance. Triturations were performed using a ball mill, with a mass dilution rate of 1:18 (set A) and 1:100 (set B), up to the 7th trituration, that is, each set contained 8 groups: A0 to A7 and B0 to B7. For each group, the triturated substrate was mixed with a fresh one in a mass ratio of 1:1. After homogenization, 18 seeds of radish (Raphanus sativus) were sown in plastic trays (31 ml cell), for each group and kept in a green house exposed to natural thermal and light variations. After 4 weeks we determine the germination rate and number of mature cotyledon. Then 5 plants from each group were selected at random to determine the following parameters: averaged leaf area, length, fresh and dry mass and pigments amount (chlorophyll a and b, carotenes). Results: Groups A0 and B0 (higher saline concentration) showed those typical effects of saline stress: lower germination ratio, immature cotyledons, smaller and shorter leaves, higher water content and less pigments. All the others groups showed similar results, for all parameters, except pigments amount. The chlorophyll to carotene ratio (CCr) showed an unexpected but interesting behavior (figure 1).Both sets showed an initial CCr growing (as expected due the saline ratio decrease), but followed by an unexpected decrement. Set B (the higher mass dilution rate, 1:100) showed a slower change, compared to set A. When we sort the results in order of saline amount we observe two peaks (figure 2), indicating that this behavior can not be explained by the saline stress.Conclusions: Trituration using plant substrate as vehicle can be suitable to assess HD effects in plant models. In this pilot study we observed unusual results regarding to the expected saline stress due the saline concentration.

Modeling Biomass Burning Organic Aerosol Atmospheric Evolution and Chemical Aging

The changes in the concentration and composition of biomass-burning organic aerosol (OA) downwind of a major wildfire are simulated using the one-dimensional Lagrangian chemical transport model PMCAMx-Trj. A base case scenario is developed based on realistic fire-plume conditions and a series of sensitivity tests are performed to quantify the effects of different conditions and processes. Temperature, oxidant concentration and dilution rate all affect the evolution of biomass burning OA after its emission. The most important process though is the multi-stage oxidation of both the originally emitted organic vapors (volatile and intermediate volatility organic compounds) and those resulting from the evaporation of the OA as it is getting diluted. The emission rates of the intermediate volatility organic compounds (IVOCs) and their chemical fate have a large impact on the formed secondary OA within the plume. The assumption that these IVOCs undergo only functionalization leads to an overestimation of the produced SOA suggesting that fragmentation is also occurring. Assuming a fragmentation probability of 0.2 resulted in predictions that are more consistent with available observations. Dilution leads to OA evaporation and therefore reduction of the OA levels downwind of the fire. However, the evaporated material can return to the particulate phase later on after it gets oxidized and recondenses. The sensitivity of the OA levels and total mass balance on the dilution rate depends on the modeling assumptions. The high variability of OA mass enhancement observed in past field studies downwind of fires may be partially due to the variability of the dilution rates of the plumes.

Mastitis Detection in Holstein Sahiwal Crossbred Cattle (Bos taurus) Using Different Brands and Dilution Levels of Liquid Anionic Surfactants

The study was conducted to evaluate the effect, consistency, and economic viability of using different brands and dilution levels of liquid anionic surfactants to detect Mastitis in dairy cattle. Fifty-five milk samples were collected and subjected to macroscopic evaluation at a cattle farm located in Sta. Maria, Bulacan, Philippines. Milk samples were brought to the Philippine Carabao Center National Headquarters and Genepool Science City of Muñoz, Nueva Ecija for Somatic Cell Count. The experiment used 10 treatments with 3 replications arranged in a Completely Randomized Design. The macroscopic evaluation results showed that liquid anionic surfactants at 30%-50% dilution levels could detect Mastitis in dairy cattle. This was validated by the somatic cell count results from PCC Dairy Laboratory. On the other hand, statistical analysis results revealed that the treatments and the control (commercial mastitis test) were comparable except for brand Z at a 40% dilution rate. Brand Z at 30% and 50% dilution rate were found to be consistent among other treatments in detecting Mastitis in dairy cattle. In terms of economic viability, brand X and brand Y at 30% were the cheapest and had the lowest production cost and highest percentage savings. The study was conducted to evaluate the effect, consistency, and economic viability of using different brands and dilution levels of liquid anionic surfactants to detect Mastitis in dairy cattle. Fifty-five milk samples were collected and subjected to macroscopic evaluation at a cattle farm located in Sta. Maria, Bulacan, Philippines. Milk samples were brought to the Philippine Carabao Center National Headquarters and Genepool Science City of Muñoz, Nueva Ecija for Somatic Cell Count. The experiment used 10 treatments with 3 replications arranged in a Completely Randomized Design. The macroscopic evaluation results showed that liquid anionic surfactants at 30%-50% dilution levels could detect Mastitis in dairy cattle. This was validated by the somatic cell count results from PCC Dairy Laboratory. On the other hand, statistical analysis results revealed that the treatments and the control (commercial mastitis test) were comparable except for brand Z at a 40% dilution rate. Brand Z at 30% and 50% dilution rate were found to be consistent among other treatments in detecting Mastitis in dairy cattle. In terms of economic viability, brand X and brand Y at 30% were the cheapest and had the lowest production cost and highest percentage savings.

Prediction for Dilution Rate of AlCoCrFeNi Coatings by Laser Cladding Based on a BP Neural Network

The dilution rate has a significant impact on the composition and microstructure of the coatings, and the dilution rate and process parameters have a complex coupling relationship. In this study, three process parameters, namely laser power, powder feeding rate, and scanning speed, were selected as variables to design the orthogonal experiment. The dilution rate and hardness data were obtained from AlCoCrFeNi coatings based on orthogonal experiments. Then, a BP neural network was used to establish a prediction model of the process parameters on the dilution rate. The established BP neural network exhibited good prediction of the dilution rate of AlCoCrFeNi coatings, and the average relative error between the predicted value and the experimental value was only 5.89%. Subsequently, the AlCoCrFeNi coating was fabricated with the optimal process parameters. The results show that the coating was well-formed without defects, such as cracks and pores. The microhardness of the AlCoCrFeNi coating prepared with the optimal process parameters was 521.6 HV0.3. The elements were uniformly distributed in the microstructure, and the grain size was about 20–60 μm. The microstructure of the AlCoCrFeNi coating was only composed of the BCC phase without the existence of the FCC phase and intermetallic compounds.

Annual assessment of the wastewater treatment capacity of the microalga Scenedesmus almeriensis and optimisation of operational conditions

The depth of the culture and the dilution rate have a striking effect on the biomass productivity and the nutrient recovery capacity of microalgal cultures. The combination of culture depth and dilution rate that allows to maximise the performance of the system depends on environmental conditions. In the current study, a response surface methodology was used to explore the relationship between the two most relevant operational conditions and the biomass productivity achieved in 8.3 m2 pilot-scale raceways operated using urban wastewater. Four polynomial models were developed, one for each season of the year. The software predicted biomass productivities of 12.3, 25.6, 32.7, and 18.9 g·m−2·day−1 in winter, spring, summer, and autumn, respectively. The models were further validated at pilot-scale with R2 values ranging within 0.81 and 0.91, depending on the season. Lower culture depths had the advantage of minimising nitrification and stripping but allow to process a lower volume of wastewater per surface area. Biomass productivity was higher at culture depths of 0.05 m, when compared to 0.12 and 0.20 m, while the optimal dilution rate was season-dependent. Results reported herein are useful for optimising the biomass productivity of raceway reactors located outdoors throughout the year.

Nitric acid solution after treating miscanthus as a growth regulator of seed peas (Pisum sativum L.)

All over the world, miscanthus is positioned as an extremely promising and rapidly renewable cellulose- containing raw material for the production of a large number of substances of chemical and biotechnological synthesis. The Institute for Problems of Chemical and Energetic Technologies of the Siberian Branch оf the Russian Academy of Sciences has been developing its own methods of treating miscanthus using diluted solutions of nitric acid. While the amount of a waste solution (liquid phase) is 20 times greater than the target product — a solid phase -- intended for enzymatic hydrolysis and further microbiological synthesis of bioethanol, bacterial cellulose and other valuable products. The hypothesis states that a nitric acid solution after treatment with miscanthus, which was neutralized with ammonium hydrate (hereinafter referred to as the preparation), is a combined lignohumic fertilizer. Testing this hypothesis has required studying the growth-regulating activity of the preparation using the example of sowing pea seeds. The results show that, depending on the degree of dilution and the exposure time, the preparation acts in two ways: either as a stimulant or as a growth inhibitor. Thus, at a dilution rate of 1:10, the preparation acts as an inhibitor, and at a dilution rate of 1:1,000,000, its effect ceases. The working range includes the dilution rate between 1:100 and 1:10,000, when an increase in germination energy and rate is observed by 2–6% compared to the control and root growth is stimulated by 21–29%, i.e. an auxin-like growth-stimulating effect is observed. With prolonged endurance during the 4th day, the preparation showed a growth-inhibiting effect, indicated by the decrease in the germination energy and rate, the length of the stems and roots of the sowing pea. The new preparation showing growth-stimulating activity under certain conditions, supposedly confirms the hypothesis that it is a combined lignohumic fertilizer.